In this paper, a continuous estimator strategy is utilized to asymptotically identify the six degree-of-freedom velocity of a moving object using a single fixed camera. The design of the estimator is facilitated by the fusion of homography-based techniques with Lyapunov design methods. Similar to the stereo vision paradigm, the proposed estimator utilizes different views of the object from a single camera to calculate 3D information from 2D images. In,contrast to some of the previous work in this area, no explicit model is used to describe the movement of the object; rather, the estimator is constructed based on bounds on the object's velocity, acceleration, and jerk. (C) 2004 Elsevier Ltd. All rights reserved.